Apes on the verge of extinction

Tuesday, 8 April 2003

Our closest relatives are hurtling towards extinction

Chimpanzee and gorilla numbers in their last African stronghold have crashed over the past 20 years due to commercial hunting for 'bushmeat' and an epidemic of Ebola fever, a disturbing new report has found.

Their fall has been so rapid, severe and under-appreciated, that the conservation status of both species should be upgraded immediately to the critically endangered category, according to the authors of the report published in the latest issue of the journal Nature.

"Without aggressive investments in law enforcement, protected area management and Ebola prevention, the next decade will see our closest relatives pushed to the brink of extinction," said Dr Peter Walsh, of the department of ecology and evolutionary biology at Princeton University in New Jersey, USA. "The stark truth is that if we do not act decisively our children may live in a world without wild apes."

The international research team's findings of a population crisis overturn previous assumptions that gorillas and common chimps had a secure haven in western equatorial Africa because the forests there were relatively intact. Gabon and the Republic of Congo alone are thought to hold about 80% of the world's gorillas and most of the common chimpanzees.

When the team surveyed ape sleeping nests at sites across Gabon over the past three years and compared the results with a national survey conducted two decades earlier - when high-density ape populations spanned the nation - it estimated conservatively that ape numbers had plunged by more than half.

The actual decline may be far greater, the report said. Only in the southwest and northeast of the country, in forests far distant from human influence, were ape numbers still high.

Those that suffered most were nearest to roads, Gabon's four major urban centres, or sites of human Ebola outbreaks - revealing that ape numbers cannot be reliably estimated by measuring the state of their forests alone.

"The primary cause of the decline in ape numbers during this period was commercial hunting, facilitated by the rapid expansion of mechanised logging," the report said. Economic migration and resettlement policies had also had an impact.

Hunting for "bushmeat" was no longer a localised village-based activity but an organised commercial industry taking advantage of logging roads to gain access to remote forests and supply salaried urban consumers. "Furthermore, Ebola haemorrhagic fever is currently spreading through ape populations in Gabon and Congo and now rivals hunting as a threat to apes," the report said.

Wildlife conservation workers have found many ape carcasses in Congo forests over the past 18 months as the Ebola epidemic has worked its way through ape populations there, especially those near where a human epidemic occurred in 2001 at Mekambo.

A study population of gorillas at Lossi once numbered 143 individuals but after exhaustive searches only seven could be found alive: seven carcasses from that group have been found since December alone.

The epidemic is now approaching the world's densest gorilla and chimpanzee populations in Odzala National Park.

Gorillas and common chimps are presently classified by the World Conservation Union as endangered. A species listed as critically endangered is expected to suffer "a reduction of at least 80% . . . within the next 10 years or three generations".

At the rate of decline exposed by the new survey, the two ape populations would be expected to fall an additional 80% within 33 years - representing only 1.5 generations for chimps and about two generations for gorillas.